To evaluate the time to treatment intervention in patients with Parkinson's Disease (PD), Multiple System Atrophy (MSA), Pure Autonomic Failure (PAF), Non-Diabetic Autonomic Neuropathy (NDAN) or Dopamine Beta Hydroxylase (DBH) Deficiency who have been previously stabilized with droxidopa therapy for symptoms of neurogenic orthostatic hypotension (NOH) (dizziness, light-headedness, or feelings that they are about to black out)